Studies of long-term survivors of cancer treated with radiation therapy and chemotherapy have led to important insights into carcinogenesis. In collaboration with the Medicine Branch, we have extended the study of second cancers after small cell lung cancer to evaluate several of the clinical parameters of screening and followup. We are also updating the data for the survivors to refine the risk estimates. In collaboration with the Radiation Epidemiology Branch, we have initiated a study of survivors of retinoblastoma who have developed melanoma. We are examining survivors and their first degree relatives and first degree relatives of individuals with retinoblastoma and melanoma who are deceased. Information on treatment for the retinoblastoma is already available, but we will also obtain sun, tobacco, and alcohol exposure information for the entire cohort. Mortality analyses have indicated that there is a significant excess of lung cancer following retinoblastoma, without any apparent excess smoking. We have continued the field work for the study of radiation-related neural tumors in a cohort of individuals who received head and neck irradiation in childhood. We plan to add up to 40 additional cohort members to the study who have developed head and neck neural tumors.